Testing the integrity of products in containers

ABSTRACT

In order to test the integrity of products in containers, several characteristics of the products are detected with physical measuring methods and a good-bad signal is produced on the basis of the measuring results, for which purpose several of the measuring results are placed in relation to each other, which can consist in the following: the deviations of the individual measuring results from a reference value, optionally after weighting and standardization are added up and the sum is compared to a threshold value. The measuring results can also form a multidimensional area in which one or several boundary surfaces separate the good value areas from the bad value areas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of the International PatentApplication No. PCT/EP2005/055838 filed Nov. 9, 2005, which claims thebenefit of German Application No. 10 2004 054 349.6 filed Nov. 9, 2004,the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a method for testing the integrity of productsin containers.

BACKGROUND OF THE INVENTION

Products in containers, in particular foods, e.g., drinks in plastic orglass bottles, can be investigated by using various physical measurementmethods. The absorption of the product at specific wavelengths of lightor infrared radiation can be measured, wherein the rotation of polarizedlight can also be measured. Similarly the absorption of X- or gammaradiation can be measured, wherein here the absorption depends on theatomic weight of the elements present in the product. By means of ahigh-frequency field it is possible to measure the dielectric constantwhich, in the case of drinks, depends in particular on the salt content.In addition to these material properties, macroscopic properties, e.g.,the fill level of the product in the container or the mass of theproduct in the container can also be measured. In the German patentapplication 10 2004 053 567.1 (application date 5 Nov. 2004, Title:Method of establishing the integrity of a product located in acontainer, our reference 36144-de), a given feature of the product isdetermined by means of two different physical measurement methods,wherein differences between the values obtained according to bothmeasurement methods of the given feature are an indication of damage tothe integrity of the product. The fill level of the product in thecontainer can be ascertained e.g., by means of X-ray absorption and bymeans of damping of an HF field. Both methods must be calibrated, as theX-radiation absorption depends on the atomic weight, and the damping ofthe HF field on the dielectric constant, of the product. If the valuesobtained with both measurement methods do not correspond to the samefill level, this means that either the atomic weight of the elementspresent in the product or the dielectric constant of the product do notcorrespond to the predefined values, i.e. to a whole or unadulteratedproduct.

A multisensor camera for quality control is known from DE-A-43 43 058 inwhich various imaging sensors operating on different physical principlessuch as b/w and colour cameras, imaging 3D sensors, imaging sensorswhich operate with penetrating radiation and imaging NIR spectroscopysensors, are used together. The sensors are arranged so that they coverthe same field of vision and corresponding image elements of the sensorsrelate to identical image elements of the product surface. The signalsof the sensors are converted image-by-image, using a classifier, into agroup image in which a code is allocated to each image element,corresponding to its membership of one of numerous, previously taughtclasses. By means of this multisensor camera it is possible to separateout shredded metal and plastic waste from a random refuse stream.

The integrity or unadulterated nature of a product in a container is atpresent determined by chemical laboratory tests, for which the productis taken out of the container.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is to test the integrity of a productcontained in a container, in particular of a product contained in asealed container.

According to the invention this object is achieved by using a method ofthe type mentioned at the outset, by correlating several of themeasurement results in order to produce the good-bad signal.

Because several features of the product are checked, integrity can beensured with greater reliability than if only a single feature ischecked.

The measurement results can be correlated in various ways. A fewpossibilities are listed below:

The measurement values are standardized to a reference value which isthe value for a defect-free product. The standardized measurementresults then give the deviation as a factor or percentage. Thedeviations of the measurement results from the respective referencevalues can be added up as scalar values. If the sum of the deviationsexceeds a threshold value, a “bad” signal is produced. It is possible toweight the individual measurement results so that the individualmeasurement methods have a varying degree of influence on the result.

The measurement results can form a multidimensional space in which oneor more interfaces separate the good and the bad value ranges from eachother. This interface can be expressed by a function with a number ofvariables corresponding to the number of measurement results. A simplecase for a mathematical equation is the spherical surface in amultidimensional space (R²=u²+v²+w²+x² . . . ). Mixed terms can howeveralso occur in this equation, i.e., the influencing of a measurementresult can depend on the value of another measurement result. Thegood-bad interface does not then have a spherical shape, but anyirregular shape. In practice it is simpler to read in a correspondingtable of values during operation.

Finally the measurement results can also be linked to each other byfuzzy logic.

All the methods suitable for investigating the product in question canbe considered as measurement methods. In the case of drink bottles theseare in particular colour, IR, X-ray or gamma spectroscopy, determinationof the rotation of polarized light through the product, determination ofthe fill level or determination of the pressure inside container.

For the determination of drinks in glass or plastic bottles, thecombination of NIR-spectroscopy, the measurement of X-ray absorption andthe measurement of the dielectric modulus has in particular provedsuccessful. NIR-spectroscopy can already be regarded for itself as aplurality of measurement methods, corresponding to the number ofinvestigated absorption peaks.

When checking individual containers filled with the product, dependingon the measurement method used, relatively large deviations must in somecases be permitted as, e.g., in the case of glass or plastic bottles,the wall thickness of the container can very greatly influence themeasurement result. According to a preferred method the measurementresults initially of one measurement method are therefore averaged overa large number of containers. For the values averaged over a largernumber of containers of the individual features of the product muchsmaller permitted deviations can be applied. With this version of theinvention systematic product defects, whether caused intentionally orunintentionally, can therefore be recorded with high reliability.

The averaging is expediently carried out on a sliding basis, i.e., theaverage value is in each case formed over a specific number of the mostrecently checked containers. For example the last hundred containers canbe used for averaging in each case.

The individual measurement results can of course additionally beevaluated in themselves in the conventional manner, i.e., if anindividual measurement result does not lie within a specific range thecontainer concerned is excluded from the further production process.

Overall the measurement results are thus used in three ways:

Each measurement result is checked for itself to ascertain whether itlies within a specific range. If it lies outside the range, thecontainer is excluded;

The measurement results of several measurement methods are correlated,e.g., the percentage deviations from the reference values concerned areadded in scalar manner, and the sum of the deviations is compared with athreshold value. They can also be introduced into a first- orhigher-order equation with a corresponding number of variables and,depending on whether the product concerned in this multidimensionalspace lies inside or outside a good-bad interface, the container isfurther processed or excluded.

The average of the measurement results of the individual measurementmethods is formed over a larger number of containers and this averagecan again, as in the first case, be compared with a reference valueseparately for each measurement method and/or the averages of themeasurement results of several measurement methods can be correlated asstated under 2.

A particular advantage of the method according to the invention is thatthe container can be tested while sealed and thus at the end of theproduction process, added to which subsequent damage to its integrity islargely excluded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a device for testing the integrity of drink bottles.

DETAILED DESCRIPTION OF THE INVENTION

A number of drink bottles 10 are transported through several inspectiondevices 21 to 25 following each other at a small distance on a conveyor12.

In the first and second inspection devices 21, 22 the fill level of thedrink in the bottle 10 is ascertained by means of X-rays and an HFfield, respectively. The values ascertained for the fill level aretransmitted to a control device 30 in which the values are compared.

In the third inspection device 23 the X-ray absorption in the lower,cylindrical area of the bottles 10 is measured.

In the fourth inspection device 24 the pressure inside the container ismeasured by means of the method known from WO 98/21557.

In the fifth inspection device 25 the absorption of a 1.06 μm infraredbeam is measured.

The measured values of all the inspection devices 21 to 25 aretransmitted to the control device 30.

As already mentioned, the signals from the first and second inspectiondevices 21, 22 are compared with each other and a fill-level-differencesignal is formed from both signals. The fill-level-difference signalmust not exceed a predefined threshold value S for each individualcontainer. The values from the other three inspection devices 23, 24 and25 are in each case compared with a reference value, wherein for eachindividual container the deviation from the reference value must notexceed 10%.

For each container, the percentage deviations reported by the inspectiondevices 23, 24 and 25 from the reference value are also added up,wherein the sum of the percentage deviations must not exceed 20%.

Furthermore the average of the fill-level-difference signals of the lasthundred bottles 10 is formed and this average must not exceed one-tenthof the threshold value S. Similarly the average of the signals from theinspection devices 23, 24 and 25 of the last hundred bottles 10 isformed and this average must deviate by no more than one-fifth from thevalue of the respective reference values which applies to the deviationof the individual bottles 10, thus 2%.

In addition the sum of the squares of the percentage deviations of thevalues averaged in each case over one hundred bottles 10 is calculatedand this sum must not exceed a predefined further threshold value. Thisthreshold value is set such that an error signal is already produced ifthe deviations of the measured values of the inspection devices 23, 24and 25 considered for themselves are still acceptable.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Itshould be understood that the illustrated embodiments are exemplaryonly, and should not be taken as limiting the scope of the invention.

The invention claimed is:
 1. A method for testing the integrity of aconsumable product that is a food or a beverage in a sealed container,the method comprising: sealing the consumable product in the container;determining a plurality of the consumable product features while sealedin the container through the use of measurements for a plurality ofdiffering physical properties directly associated with the consumableproduct by a plurality of differing inspection device types;standardizing results of the plurality of the measurements for thediffering physical properties of the consumable product to respectivereference values that are the measurement values of the differingphysical properties for a defect-free specimen of the consumableproduct; totaling up deviations of the standardized measurement resultsfrom the respective reference values to obtain a correlated result forthe consumable product that is based on the combined measurements forthe differing physical properties; and obtaining an indication for theproduct status on the basis of comparing the correlated result to athreshold value and producing a signal or alarm if the correlated resultexceeds the threshold value.
 2. The method of claim 1, wherein theplurality of differing physical properties measured include one or moreof color, infrared, X-ray or gamma spectroscopy, the rotation ofpolarized light through the product, the fill level, and the pressureinside the container.
 3. The method of claim 1, wherein the plurality ofproduct features determined as a result of the plurality of differingphysical property measurements forms a multidimensional space in whichone or more interfaces separate good and the bad value ranges from eachother.
 4. The method of claim 1, wherein the standardized measurementresults are linked to each other by fuzzy logic.
 5. The method of claim1, wherein the plurality of product features determined as a result ofthe plurality of differing physical property measurements are averagedover a plurality of containers.
 6. The method of claim 5, wherein one ormore of the plurality of product features are evaluated separately foreach product in a container.
 7. The method of claim 6, furthercomprising: averaging the differing physical property measurementresults over several products; and correlating the averaged measurementresults in order to produce a further good-bad signal.
 8. The method ofclaim 1, wherein the step of totaling up the deviations of thestandardized measurement results from the respective reference valuesinvolves the addition of the deviations as scalar values.
 9. The methodof claim 8, wherein the standardized measurement results of theplurality of differing physical property measurements are weighted. 10.The method of claim 8, wherein the totaling step involves the additionof the squares of the deviations.
 11. The method of claim 8, wherein thetotaling step involves the addition of the higher powers of thepercentage deviations.
 12. The method of claim 1, wherein the totalingstep involves the addition of percentage deviations.
 13. The method ofclaim 1, wherein the product being tested is a liquid.